Here is a basic thobber:
((cos(time/2)+1)*x)+((cos((time-(3.141*2))/2)+1)*(100-x))
Here is using the same trick to switch between two patterns:
((cos(time/50)+1)*(A*1000))+((cos((time-(3.141*50))/50)+1)*((x-50)^2+(y-50)^2))
Unfortunately, this trick doesn't work well with patterns with high values, and thus most animated patterns don't work.
It works like this:
((cos(time/p)+1)*q)+((cos((time-(3.141*p))/p)+1)*Q)
The cos(...)+1 part in both sections is in charge of timing. In the second part we subtract pi * p, which is half the period, from time to make it start at the half point of the cycle.